category artbook -> meta

BUR #4780 has been approved by @evazion.

category artbook -> meta

Same case as doujinshi in topic #18095

The tag refers to the source of an image rather than denoting a visible feature. Consistent with novel_illustration, magazine_scan.

I also request removing the word 'Official' from the wiki as that description excludes original artbooks.

This bulk update request is pending automatic rejection in 5 days.

This bulk update request has been rejected because it was not approved within 60 days.

The bulk update request #4780 (forum #181207) has been rejected by @DanbooruBot.

The bulk update request #4780 (forum #181207) has been approved by @evazion.